Re: Function Based Index
- From: Purav Chovatia <puravc@xxxxxxxxx>
- To: Jonathan Lewis <jonathan@xxxxxxxxxxxxxxxxxx>
- Date: Thu, 20 Sep 2012 21:30:28 +0530
Jonathan,
Can you pls help me understand how did you figure out the foll.:
- that the row for table is much larger than the row estimate for the index
- the cost of the table visits have been added to the cost of the range scan
Thanks.
On Fri, Sep 14, 2012 at 6:54 PM, Jonathan Lewis <jonathan@xxxxxxxxxxxxxxxxxx
> wrote:
>
> The fact that the row for the table is much larger than the row estimate
> for the index used to get to it suggests that you didn't collect stats on
> the hidden column underpinning the table when you created the index. The
> plan may have changed the following morning because of an overnight stats
> collection that rectified this mismatch. It's interesting, though that in
> this case the cost of the table visits have been added to the cost of the
> range scan - but perhaps that's a version thing.
>
> Regards
>
> Jonathan Lewis
> http://jonathanlewis.wordpress.com/all_postings
>
>
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